As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO WAS REMOVED DUE TO THE TACH PEGGING AT 100 PERCENT ON START UP. INVESTIGATION REVEALED ONE OF THE TACH LEADS WAS CHAFED THRU ON THE OPPOSITE PIN ON THE TACH POINTS. THE CLEARANCE WAS ALSO FOUND BELOW LIMITS AT THE TACH POINT: 0.012-0.015.